I am likely younger than your sisters, but in pretty much every other case we're very similar, aside from the fact that we don't have any type II diabetes in the family.

I am the fat sister. My sister is also fat. We have two brothers who are normal weight. I know being fat is associated with many poor health outcomes. However, I am still fat. I worry and stress about it every day. Unless your sisters are of lower than normal intelligence, they also know.

So why don't we just diet?

There are a thousand reasons. In my case I'm disabled, and the disability came long before the fat. I also work close to 60 hours per week. For another fat person it might be depression, lack of motivation, eating disorders, etc.

If you're going to tell me you're concerned about me, I want to hear how you can actually help. Money is very, very tight, so can you maybe help me afford pre-made healthier meals? I'd love to eat healthier but I can't afford to spend much time or energy on food because I'm already exhausted.

I frequently choose between working and working out. Working always wins because I need to keep my job to pay the bills.

A friend of mine gained a bunch of weight when she became the primary caretaker for her mother, and part-time caretaker for her partner's mother (in addition to her full-time job). She knows she eats emotionally to deal with it, but she doesn't know what else to do. Several family members have had the weight conversation with her but not one has offered to either help out more with the ailing parents, or help her afford therapy.

People in fat acceptance movements often call this concern trolling, because it can really overlap with that sort of behavior. And honestly, fat people hear it all the time.

But if you feel strongly enough about it to bring it up, be prepared to have a response to the reasons they give for not wanting to/being able to change.